Since their early 20s, Emily Watson and Olivia Williams’ careers have run on parallel tracks. Born one year apart, they first got to know each other by pondering their futures together on a patch of grass outside The Black Swan pub in Stratford-upon-Avon. “We met at the Royal Shakespeare Company, in the early ’90s, where we were in different plays in different seasons,” says Williams. The two never ended up on stage together. “Partly because there aren’t that many scripts around for two leading ladies of the same age,” adds Watson.

Their paths would soon cross again, as Williams made her foray into Hollywood, with Kevin Costner’s The Postman and Wes Anderson’s Rushmore, around the same time as Watson was leveraging her breakout success in Lars von Trier’s Breaking the Waves. “I was staying at the Four Seasons and we had a cosmopolitan, as was the fashion then,” recalls Williams. “There’s something bonding about those years for those of us for whom it felt like slight pioneering into Hollywood in the late ’90s. Every generation has the people who turn up in Los Angeles, and in those days you had a Thomas Guide on your lap.”

As they spent the next two decades building notable careers—once even sharing billing, if not screen time, in Joe Wright’s Anna Karenina—what neither foresaw was that a science fiction epic would unite them professionally. Although Dune: Prophecy was poised to follow in the ambitious footsteps of Denis Villeneuve’s interpretation of Frank Herbert’s famous novels, what drew Williams to the project was first and foremost Watson. “I literally came to [Dune] through a phone call from my agent, who also represents Emily Watson, saying, ‘Do you want to do a job in Budapest with Emily?’” says Williams. “That was how it was sold to me.”

The prequel series about the formation of the Bene Gesserit, an order of women who become the puppet masters of the great houses of the Empire on Dune, offered Watson and Williams plenty to dig their teeth into, as the two morally ambiguous sisters running the de facto cult.

“I started reading these scripts, thinking, ‘Oh, this is a little bit out of my lane, but this is a really interesting woman. She’s powerful and damaged and got one hell of a mission,’” recalls Watson, who plays Valya Harkonnen, the Sisterhood’s Reverend Mother Superior that seeks to position a Sister on the Council of the Imperium, while restoring the reputation of her disgraced family. “It feels like different territory for me and that’s always a fantastic challenge—to find something that has a completely different center of gravity, rhythm and voice from stuff I’ve done before.”

Williams, who plays Valya’s younger sister Tula, immediately tapped into the frustrations of a sibling that, despite her sacrifices for the cause, is still frequently underestimated. “Show me a younger sister that doesn’t feel undermined,” says Williams. “The worst thing for a child is to be ignored. You’d rather have negative attention than no attention at all. And being the good girl meant Tula was ignored.”

With their lingering trauma and steely resolve, these two sisters are a combustion waiting to happen. “These are middle-aged women, who have lived a life with years of disappointments, resentments and rejections to build up a really complex set of angsts that need to have an exit,” says Williams. “Throw into all that the fact that these women can speak to their ancestors, which adds another few thousand generations of angst and repression, and you have a really tasty plot.”

To get an understanding of Dune’s vast legacy and cultural significance, they turned to showrunner Alison Schapker, a sci-fi veteran with titles like Fringe, Altered Carbon and Almost Human to her name. As a fan of Herbert’s series since her formative years, Schapker had found herself creatively drawn to the Schools of Dune trilogy, added in the 2010s by Brian Herbert and Kevin J. Anderston, focusing on the Harkonnen legacy. “It’s anchored in a very specific relationship between Valya and Tula, who are part of a family that will one day become the monstrous villains of Dune,” explains Schapker.

The roads that eventually lead us to Vladimir Harkonnen’s (played by Stellan Skarsgård in the most recent Dune films) ruthless reign, have their beginnings in the two time periods that Prophecy explores. In the earlier timeline, Valya (Jessica Barden) is recruited by a charismatic leader to join a mysterious religious group. In the latter, she has become its driving force. “We see that the choices you make at one point in time have ripple effects and unintended consequences, and that we’re all a sum total of the baggage we carry through history,” says Schapker, who has been able to build out the world in collaboration with the Herbert estate. “As I get older, the kind of choices people make, and how time affects those choices, is what I am more and more interested in exploring.”

That her two leads came to the universe lacking the fandom of some their followers did not worry Schapker. “I think it was a fun challenge for them to take a sci-fi world and then to ground it,” she says. It was also a way to test the material, which Schapker hoped would not alienate those unfamiliar with the franchise. “We sought to make a show that those who are just checking out the Dune universe for the first time, could jump into as a point of entry,” she says.

In Prophecy a near century has passed since humanity defeated “thinking machines” and gender equality seems all but a distant memory. The Council of the Imperium is run by men quietly advised from the sidelines by members of The Sisterhood—human lie detectors, if you will— who whisper into the ears of those in power. Yet, in terms of on-screen representation, the series performs well above the norm. Two women being forced to resort to underhanded machinations to achieve their goals more than passes the Bechdel test, and, as studies show that women start disappearing from the television landscape around the age of 40, a series featuring two middle-aged female leads is exceedingly rare in today’s entertainment landscape.

“You’ve heard this a million times, but [a story] starts, ‘There was a man who…’ and he might have a wife, he might have a mother, he might have a daughter, he will probably have a mistress—but the mistress will be young and bossomy and the wife will be tired and haggard and will not understand him,” says Williams. “There’s no real space for two fifty-year-old women. Even if you have a movie with a woman and her best friend, the two roles will not be of equal standing. That’s why this was an extraordinary story.”

Fittingly, for a show about how women wield their power, Prophecy has presented the two actors with an opportunity to create the working environment they, themselves, have longed for, as they lead a cast of young women, many of them at the start of their careers. “Being able to set the tone and look after all the young actors, make sure everybody’s feeling seen and do it in a way that you would always want it to be done, but it doesn’t often come out like that, was a treat,” says Watson.

With the possibility of a long future together, Watson and Williams are far from concerned about growing weary of their joint venture—now that their paths have finally converged.  “Allison, and particularly Jordan [Goldberg], write beautiful scenes that are interesting to act,” says Williams. “And the Dune universe provides the most extraordinary palette of colors, places and situations. There’s no danger of getting bored or it being repetitive, because the possibilities are endless.”

Dune: Prophecy is now streaming on Max.